Transitioning an empty lot to a homestead in three days might seem like a fantasy, but as housing-focused nonprofits such as Habitat for Humanity explore 3D-based printing of homes, the concept moves from fiction to solution.
Through the 3D printing process, 168 or so overlaid layers of a thick concrete solution can be pushed through the nozzle of a massive printing unit “like when you’re writing ‘Happy Birthday’ on a cake,” explained Janet V. Green, CEO of Newport News, Virginia-based Habitat for Humanity for Peninsula and Greater Williamsburg.
“It took literally hours to do the entire 3D printing of a 1,200 to 1,300-square foot house,” she added.
Housing advocates, including Green, point out the misconception above. The concrete mixture must cure. What is printed is a frame, albeit a very solid frame. Plumbing, electric, and niceties such as doors and windows still need to be installed by hand, and that work is often completed by professional subcontractors.
Even so, the 3D printing process compares favorably to building a traditional “stick-built” home, in which construction can take weeks and requires far more volunteers. “The fact that this [process] runs on a computer, and can be run on a phone from anywhere, means we’ll need less personnel to do it faster and complete a home,” Green said.
Those volunteers probably, within the next few years, look very different from those working at typical Habitat construction sites. “My grandson has no desire to go into the construction trade,” Green said. “But, he’s very computer savvy.”
Habitat for Humanity for Peninsula and Greater Williamsburg has competed three houses — the first constructed in 2021, and two built on side-by-side lots in 2023. “The cost efficiencies and improvements were incredible from the first house to the second, and even from the second to the [nearly contemporaneous] third,” Green said.
Building houses simultaneously allows Habitat to negotiate efficiencies on certain expenditures, such as heavy machinery, and provides steady work and support for volunteers. Once the 3D printing process moves from novel to standard for this branch of Habitat, Green estimates that its current output of between 10 and 15 homes a year could double by 2027. Even better, the cost of a 3D-printed home should come in at around 15% less than that of a traditional stick-built one.
The cost savings are important, both for Habitat’s operating budget and because Habitat houses are sold, not given, to recipients. “They pay the full price, but their monthly payments [are capped at] 30% of their income,” and can be less, Green said. The houses come with zero-interest mortgages. To prevent flipping, Habitat holds most of the equity of its homes for the first 15 years of the mortgages.
Habitat is achieving the 3D printing cost savings without compromising quality, officials said. Each house is equipped with monitoring devices provided by nearby Virginia Tech University that track a variety of data, including humidity, gasses, sound, and light. “We would like to share that data worldwide with people interested in more innovative ways of focusing on affordable housing,” Green said.
The resulting houses blend in with others in their areas. “You wouldn’t know they were printed by machine,” Green said. If anything, the houses are more desirable than traditionally built structures. Those in the Williamsburg area were independently appraised at $50,000 more than other houses in the same neighborhood.
There are other savings associated with 3D home printing. “There’s so much wasted material (in regular construction) — concrete is not a friend of the environment,” Green said.
Her organization’s biggest challenge is the lack of available, buildable land. Using 3D printing to construct units is more efficient if the organization can build multiple homes in a concentrated area, which requires less movement of heavy equipment and the ability to quickly redeploy human and other construction resources from one structure to another.
That’s not the only hurdle. The organization’s forays into 3D printing are constrained, at least somewhat, by the availability of the printing units. Eden Villages, a Springfield, Missouri-based nonprofit that seeks to create what Chief Visionary Officer Nate Schlueter calls “ultra-affordable” communities, overcomes that barrier by owning at least two of every type of machinery needed to construct the homes. “We have access to donors who give us money for the machines,” he said. “We have about $2.5 million invested in this idea.”
Eden Villages communities consist of groups of homes that are smaller than those built by Habitat. An Eden Villages home will usually run closer to 400 square feet. Residents are welcome to live in their homes for as long as they’d like but the $325 monthly rent does not give them equity, unlike homes constructed by Habitat.
The organization’s focus has so far been on modular homes, as it has built in Eden Villages One, a 31-unit modular home community in Wilmington, North Carolina and Eden Villages Two, a 24-home unit in Springfield, Missouri. In spring 2024, Schlueter anticipates constructing its first printed village – Eden Three, a community of 24 duplexes, which will be followed by a fourth location currently anticipated at 16 units.
Small villages will allow the nonprofit to create a community that embraces a quirk of 3D home printing. “A 3D printer typically doesn’t like to do hard 90-degree corners,” Schlueter said. “In some sense, it provides freedom for an architect to do some crazy stuff. But you still have to marry that to a roof that’s traditionally framed,” Schlueter explained. Engineers at Eden Villages work with architectural students from the Hammons School of Architecture at Drury University in Springfield, Missouri to make sure the homes are structurally sound.
“We haven’t printed homes that anyone lives in,” Schlueter said. “We’ve spent the last year testing structures to make sure, before we put somebody in them, that they’re going to hold up.”
Schlueter estimated that for any given unit the time from printing to move in, if all goes well, would be around 30 days. That period reflects the time the concrete would need to cure, as well as plumbing, electricity, and roof installation. The resulting homes are stronger than most. They are rated to withstand vertical and horizontal water penetration, as well as the most destructive category of tornados.
They’re also less expensive. Their durability lowers maintenance costs, and their basic design is more energy efficient. Even before that, overall savings in construction costs should make them around 40% cheaper than traditional homes, according to Schlueter.
Part of that difference is the result of building efficiencies, but the comparatively lower cost also reflects escalating costs of traditional construction seen in the post-COVID period, he added.
All this said, 3D home printing isn’t a perfect solution for every homelessness-eradicating nonprofit. Habitat for Humanity Central Arizona did a proof-of-concept printing of one home in Tempe, Arizona two years ago. The build was a success — it currently has a family in it — but the chapter is not actively pursuing building more.
“We were looking for a way to build more efficiently, more affordably and more sustainably,” said Dusty Parsons, chief marketing officer at Habitat for Humanity Central Arizona. “We were approached by Arizona State University representatives who asked if we wanted to try out 3D printing. It didn’t take us long to say yes. We didn’t achieve any of those three things with this first one. But we felt like we had to try.”
There was nothing wrong with the home. It is energy efficient. “I don’t think they had to turn on their air conditioner until mid-June,” according to Parsons — and “solid and keeping [the residents] safe.”
But the first home did not yield the efficiencies for which Parsons had hoped. Part of the reason was the nature of this Habitat chapter’s work. “We work a lot in infill,” Parsons said, referring to the one-off odd lots where it builds homes. Often the lots are constrained by other structures around them, making it unwieldy to move the large printing units into place.
Other considerations come into play, especially in areas that currently have developments. “International Building Codes haven’t caught up with this,” Parsons said. “None of this is recognized. We had to get a variance and work very closely with City of Tempe to make sure we’re going to be able to do this and get permits. That can be expensive for any developer, nonprofit or commercial.”
The Tempe unit did not require Habitat for Humanity Central Arizona to take a loss, but that was largely due to donations from interested parties wanting to be part of a test project. Parsons was not sanguine that his organization would be able to easily replicate the low-cost nature of future projects.
“We wouldn’t be opposed to trying this again, but it’s got to get more efficient for us,” Parsons said. “We’re trying to tackle one of Arizona’s most pressing issues right now: home affordability. We felt like it was a moonshot opportunity to try something new. Since then, we’ve seen more and more stories about 3D printing in other places in more commercial sector, and we’re really excited for where the technology will go.”
